Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09C—RECLAMATION OF CONTAMINATED SOIL
  • B09C1/00—Reclamation of contaminated soil
  • B09C1/02—Extraction using liquids, e.g. washing, leaching, flotation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09C—RECLAMATION OF CONTAMINATED SOIL
  • B09C1/00—Reclamation of contaminated soil
  • B09C1/002—Reclamation of contaminated soil involving in-situ ground water treatment
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S210/00—Liquid purification or separation
  • Y10S210/918—Miscellaneous specific techniques
  • Y10S210/922—Oil spill cleanup, e.g. bacterial
  • Y10S210/925—Oil spill cleanup, e.g. bacterial using chemical agent

Definitions

• the present invention relates to a method for removing dense non-aqueous phase liquids in porous media by the use of surfactant- enhanced aquifer remediation. More particularly, the present invention involves the use of solutions which produce generally neutral buoyancy during the cleanup of dense non-aqueous phase liquids to control vertical migration and thus enable surfactant- enhanced aquifer remediation in aquifers lacking a clay bottom layer or other form of aquiclude to prevent downward migration of the solubilized dense non-aqueous phase liquids. Additionally, such a method of aquifer remediation can also be used on aquifers having an aquiclude.
• Chlorinated solvents such as trichloroethylene and perchloroethylene and other types of organic liquids are common at such sites and, if not removed, can filter down into groundwater supplies, rendering the water unfit for consumption and other uses.
• FIG. 1A shows a table of solubilization of perch!
• This application of surfactant- enhanced aquifer remediation is very effective, but nevertheless does not address the concern over uncontrolled, vertical migration of the free-phase DNAPL (during mobilization), or of a microemulsion containing the DNAPL compounds (during solubilization) in aquifers not underlain by an aquiclude.
• the technology described herein is designed to address such concerns over vertical migration.
• the application of surfactant-enhanced aquifer remediation described here is one in which only solubilization of the DNAPL compounds occur. That is, this technology is specifically designed to ensure that no mobilization of the DNAPL occurs.
• a well 10 is formed on one side of the spill area 20 and is configured for flooding the spill area with a surfactant, such as one of those described above.
• a surfactant such as one of those described above.
• the dense non- aqueous phase liquid As the dense non- aqueous phase liquid is solubilized, it is carried to an extraction well 30 disposed on the opposite side of the spill area 20. While the solubilized dense, non-aqueous phase liquid moves through the aquifer, it may continue to migrate vertically due to the microemulsion's density relative to the surrounding groundwater. Generally, a sufficiently thick aquiclude 40 such as a clay or shale layer will preclude its continued migration. Thus, despite such vertical migration of the dense, non-aqueous liquid contaminants, over time the entire spill area is substantially cleaned of the contaminant if wells are screened all of the way to the aquiclude.
• It is still yet another object of the present invention which enables prediction of vertical migration of the solubilized dense non-aqueous compounds and enables manipulation of the vertical migration by controlling design parameters of the remediation method to enable extraction of the contaminants through an extraction well.
• the dense, non-aqueous phase liquids can be safely removed without risking contamination of the soil and water sources below the contaminated site.
• a method for remediation of dense non-aqueous phase liquids including forming a well for introduction of a solubilizing solution having a surfactant and an alcohol or other light co-solvent.
• the surfactant is selected to solubilize the dense non-aqueous phase liquid.
• the alcohol or other light co-solvent is selected and injected in a sufficient quantity to provide the microemulsion with a reduced density for the purpose of giving it a substantially neutral buoyancy with respect to groundwater.
• Adding co-solvents to the injected surfactant also provides other benefits, including improving the phase behavior of the resulting microemulsion phase.
• the neutral buoyancy of the microemulsion prevents the downward movement which is typical of the solubilized dense non-aqueous liquid contaminants in the surfactant- enhanced aquifer remediation.
• the risk that any significant amount of the solubilized dense, non-aqueous phase liquid will migrate vertically can be controlled.
• the buoyancy by controlling the injection rate, injected fluid viscosity, microemulsion phase density and the well spacing, the buoyancy, and thus vertical mobility, can be controlled to provide desired extraction of dense, non-aqueous phase liquid constituents in a microemulsion while minimizing expense and treatment time.
• FIG. 1A is a table showing the solubilization of perchl oroethylene by various surfactant solutions
• FIG. IB shows a table showing the enhancement of dense non- aqueous phase liquid removal by use of surfactants
• FIG. 1C shows a schematic representation of the sol ubi 1 ization/surfactant-enhanced aquifer remedi ation in accordance with the teachings of the prior art
• FIG. 2 is a schematic representation of a method of remediation of dense non-aqueous phase liquids in porous media through minimization of buoyancy effects in accordance with the present invention
• FIG. 3A is a graph demonstrating vertical migration as a function of the scaling groups N g and R L where the mobility ratio is 0.5;
• FIG. 3B is a graph demonstrating vertical migration as a function of the scaling groups N g and R L where the mobility ratio is
• FIG. 3C is a graph demonstrating vertical migration as a function of the scaling groups N g and R L where the mobility ratio is 2.
• FIG.2 there is shown a schematic representation of a method of remediation of dense non-aqueous phase liquids in porous media through minimization of buoyancy effects in accordance with the present invention.
• dense non-aqueous phase liquids such as perchl oroethylene or trichl oroethylene
• a first well 120 is drilled into the soil adjacent the contaminated site 110.
• the first well 120 is configured for the introduction into the groundwater supply of a solution containing a surfactant and a light co-solvent (typically an alcohol).
• a solution typically an alcohol
• the solution will also often contain a polymer for altering the solution's viscosity.
• a second well 130 is drilled on the opposite side of the contaminated site 110.
• the second well 130 is configured for withdrawing contaminated groundwater and the microemulsion that a forms in-situ when the surfactant and light co-solvent solubilize the dense non-aqueous phase liquid constituents.
• the contaminated groundwater is then treated by air stripping or some other treatment system 140 to clean the water.
• first and second wells, 120 and 130 are conventional and are commonly used in contamination removal.
• the number of wells is dependent on the size of the spill and it is not uncommon to have multiple wells formed on opposing sides of the contaminated area 110.
• the method for utilizing the wells to significantly improve the ability to clean dense non-aqueous phase liquids in aquifers lacking an aquiclude is unique.
• the present invention enables the user to control a host of variables to efficiently and effectively clean the dense non-aqueous phase liquids without the risk of vertical migration which has previously prevented the use of surfactant-enhanced aquifer remediation on aquifers lacking an aquiclude.
• the screened interval of each well and the distance between the wells depends upon the specific characteristics of the aquifer and the location and volume of the non-aqueous phase liquid.
• This initial information can, for example, be obtained by the use of partitioning and conservative interwell tracer tests which are well known in the art. These tests can measure the volume and distributions of the dense non-aqueous phase liquid in the interwell zone (i.e. the area between the opposing wells).
• a microemulsion is any stable mixture of surfactant, co-solvent, non-aqueous phase liquids, and water.
• a cosolvent that is significantly lighter than the contaminant to be solubilized is added to the injected chemicals.
• the microemulsion has substantially the same buoyancy as the groundwater which reduces or eliminates its tendency to migrate vertically. In other words, sufficient quantities of the lighter cosolvent counteract the heavier weight of the contaminants to help the microemulsion to remain in substantially the same vertical position.
• testing in a laboratory setting can be undertaken to ensure that the projected vertical mobility of the microemulsion is accurate, thereby ensuring that the extraction well(s) are sufficiently deep and screened appropriately to remove even that portion of the microemulsion which demonstrates some vertical mobility.
• excellent agreement has been obtained between the predicted and observed migration in experiments already conducted. This demonstrates that hydraulic control over the contaminant can be maintained, and that dense non-aqueous phase liquid remediation can be addressed in even those aquifers lacking a clay or shale aquiclude with little risk of downward migration of the contaminants.
• a more dense phase i.e., a microemulsion that contains solubilized dense non-aqueous contaminants
• N ⁇ a gravity number
• M the mobility ratio
• R L an effective aspect ratio
• FIG. 2 is the aquifer thickness, and k rm ⁇ is the relative permeability to the microemulsion phase and k rw is the relative permeability to the water phase within the aquifer. Also within these dimensionless groups are four design parameters: 1) microemulsion phase density, ⁇ m ⁇ ;
• the value of the scaling groups By controlling the value of these design parameters, we are able to control the value of the scaling groups. It is important to realize that the specific value of any given parameter within the scaling group is unimportant; it is the value of the group that describes the vertical migration. It should further be noted that the exact form of the scaling groups is unimportant.
• the method shows how the design parameters affect vertical migration. Therefore, the amount of migration of the contaminant can be manipulated. Manipulating the amount of migration of the contaminant can be accomplished by the well positioning and screen depth, control of the injection and extraction rates of the wells, and of the microemulsion density and viscosity.
• Non-dimensional izing the governing equations shows that vertical migration of the microemulsion is a function only of these three scaling groups. However, it does not indicate what the relationship specifically is. Therefore, numerical simulations of vertical migration as a function of these scaling groups has been conducted. Results are shown in Figures 3A through 3C. These figures show that vertical migration of the contaminant is predictable and is a function of the scaling groups, where in this example the mobility ratio is 0.5, 1, and 2, respectively. Experiments which have been performed validate the theory. The experiment's predicted migration agreed within 5% of the observed migration in the experiment. Therefore, in light of the present invention, the migration of contaminants solubilized in a microemulsion in the subsurface is a predictable quantity, and a remediation strategy can be designed that captures the full plume without the need for an aquiclude.
• the wells are drilled adjacent the contamination site 110 (FIG. 2) as set forth above.
• the surfactant is then combined with the light co-solvents and the polymer.
• the surfactant may be those typically used with surfactant-enhanced aquifer remediation, such as those set forth in FIG. 1A.
• the light co-solvent will preferentially be an alcohol, such as ethanol or isopropanol, and will be used in sufficient quantity to lower the microemulsion density to some predetermined value wherein the risk of downward vertical migration below the area of the aquifer being treated is substantially reduced.
• Adding water-sol uable polymer to the injected solution increases its viscosity and the viscosity of the microemulsion which forms in-situ.
• the preferred polymer type is a water-soluble biopolymer which is highly biodegradable, such as xantha gum. There are many other suitable polymers that could also be used for this purpose.
• the present invention not only enables the relatively accurate determination of vertical mobility of the microemulsion, it also enables those operating the wells to manipulate the buoyancy of the dense non-aqueous liquid contaminants by the use of the alcohol to obtain substantially neutral buoyancy. This, in turn, allows for the remediation of aquifers lacking an aquiclude with surfactants without the risk of spreading the contaminants.
• substantially neutral buoyancy may be attained in various ways. The easiest to see is by reducing the microemulsion density to that of groundwater. In that case, the microemulsion has exactly zero tendency for further vertical migration. An alternative is to reduce the microemulsion density to some specified design value (greater than that of groundwater), and then to increase the relative magnitude of the horizontal driving force. Either of these options results in a decrease of the relative importance of buoyancy.
• the horizontal forces are manipulated by increasing the injection rate, increasing the injected fluid viscosity (by adding polymer), or decreasing the well spacing.
• the equations used to determine gravity number, mobility ratio and effective aspect ratio may typically be programmed into a computer. Samples will be taken to determine the permeability of the aquifer and other site-dependent variables.
• those conducting the site clean-up can adjust parameters of well location, injection rate, etc. and determine the most effective engineering designs for cleaning the contaminated site. If desired, sensors or periodic testing could be provided so that the computer continually controls such factors as injection rate, viscosity of the injected solution, etc.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Soil Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Water Supply & Treatment (AREA)
• Hydrology & Water Resources (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Processing Of Solid Wastes (AREA)
• Water Treatment By Sorption (AREA)
• Artificial Filaments (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)

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• 1997
  • 1997-10-22 US US08/956,297 patent/US5993660A/en not_active Expired - Fee Related
  • 1997-11-05 AU AU55847/98A patent/AU727559B2/en not_active Ceased
  • 1997-11-05 AT AT97952173T patent/ATE257546T1/de not_active IP Right Cessation
  • 1997-11-05 ES ES97952173T patent/ES2213230T3/es not_active Expired - Lifetime
  • 1997-11-05 WO PCT/US1997/019941 patent/WO1998020234A1/en not_active Ceased
  • 1997-11-05 CA CA002270920A patent/CA2270920A1/en not_active Abandoned
  • 1997-11-05 EP EP97952173A patent/EP0937193B1/de not_active Expired - Lifetime
  • 1997-11-05 DE DE69727152T patent/DE69727152D1/de not_active Expired - Lifetime

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